<template>
  <div class="pagination">
    <!-- 前半部分 -->
    <button :disabled="pageNo==1" @click="$emit('getPageNo',pageNo-1)">上一页</button>
    <button v-if="startNumAndEndNum.start>1" :class="{active:pageNo==1}">1</button>
    <button v-if="startNumAndEndNum.start>2">···</button>
    <!-- 中间部分 -->
    <button v-for="(page,index) in startNumAndEndNum.end" :key="index" v-show="page>=startNumAndEndNum.start" @click="$emit('getPageNo',page)" :class="{active:pageNo==page}">{{ page }}</button>
    <!-- 后半部分 -->
    <button v-if="startNumAndEndNum.end<totalPage-1">···</button>
    <button v-if="startNumAndEndNum.end<totalPage" :class="{active:pageNo==totalPage}">{{totalPage}}</button>
    <button :disabled="pageNo==startNumAndEndNum.end" @click="$emit('getPageNo',pageNo+1)">下一页</button>
    
    <button style="margin-left: 30px">共 {{ total }} 条</button>
  </div>
</template>

<script>
  export default {
    name: "PaginationPage",
    props:['pageNo','pageSize','total','continues'],
    computed:{
      //共有多少页
      totalPage(){
        return Math.ceil(this.total/this.pageSize)
      },
      startNumAndEndNum(){
        const {continues,pageNo,totalPage}=this;
        let start=0,end=0;
        //不正常现象，当前页大于总页数
        if(continues>totalPage){
          start=1;
          end=totalPage
        }else{
          start=pageNo-parseInt(continues/2);
          end=pageNo+parseInt(continues/2);
        }
        if(start<1){
          start=1;
          end=continues
        }
        if(end>totalPage){
          end=totalPage;
          start=totalPage-continues+1
        }
        return {start,end}
      }
    }
  }
</script>

<style lang="less" scoped>
  .pagination {
    text-align: center;
    button {
      margin: 0 5px;
      background-color: #f4f4f5;
      color: #606266;
      outline: none;
      border-radius: 2px;
      padding: 0 4px;
      vertical-align: top;
      display: inline-block;
      font-size: 13px;
      min-width: 35.5px;
      height: 28px;
      line-height: 28px;
      cursor: pointer;
      box-sizing: border-box;
      text-align: center;
      border: 0;

      &[disabled] {
        color: #c0c4cc;
        cursor: not-allowed;
      }

      &.active {
        cursor: not-allowed;
        background-color: #409eff;
        color: #fff;
      }
    }
  }
</style>